The goal of this proposal is to investigate prospectively the course of body dysmorphic disorder (BDD) and its delusional disorder variant in 200 adults and adolescents over 3 to 4 years. Body dysmorphic disorder, an often-delusional preoccupation with an imagined or slight defect in appearance, is a distressing, impairing, and costly disorder that is more common than is generally recognized. Such investigation is important because BDD appears to often be chronic and to cause considerable morbidity over the life span. It is associated with high rates of social and academic/occupational impairment, being housebound, psychiatric hospitalization, suicidal ideation, and suicide attempts. Only minimal data are available on the longitudinal course and outcome of BDD. Thus, little is known about the clinical course of symptom severity, psychosocial functioning, and quality of life. This proposal's broad objective is to conduct the first prospective longitudinal study of the course and outcome of BDD and its delusional variant (delusional disorder, somatic type). The specific aims are the following: 1) map patterns of course for BDD; 2) identify predictors/mediating variables associated with remission and relapse; 3) describe surgical, dermatologic, other medical, and psychiatric treatment received, and examine the association between treatment and course; and 4) describe psychosocial functioning and quality of life over time, and assess their relationship with BDD symptom severity and delusionality. Subjects will be carefully evaluated at annual intervals with reliable and valid instruments that obtain detailed information on symptom status and severity, diagnostic status, treatment utilization, psychosocial functioning, quality of life and other domains. The proposed study will be the first prospective study of the course of BDD. Findings from the study will shed new light on clinically and theoretically important questions about a severe and relatively common, yet underrecognized and understudied, disorder.